1. Field of the Invention
This invention relates generally to a mounting for supporting an antifriction bearing journalling a rotary shaft, and more particularly to a cantilever mounting for resiliently supporting the bearing for radial movement.
2. Description of the Prior Art
One of the principal sources of vibration in equipment having high speed rotating shafts, such as turbomachinery, is unbalance of the shaft. The unbalance can excite one or more critical frequencies of the rotary shaft and induce resonance in the shaft that may be tuned to the shaft's running frequency.
The effects of unbalance may be minimized by resiliently supporting, for radial movement, one or more of the bearings journalling the shaft. Cage type cantilever mountings have found particular utility for resiliently supporting the bearings journalling a shaft assembly of a turbine engine. An explanation of the operation of such cantilever mountings may be found in the Society of Automotive Engineers Paper No. 382B, published 1961, entitled "Gas Turbine Shaft Dynamic," and authored by Glenn Hamburg and Jim Parkinson. Cantilever mountings are also disclosed in U.S. Pat. No. 2,922,278; 3,005,668; 3,205,024; and 3,416,723. In each of the cited disclosures the cantilever mounting is an annular cylindrical member having a fixed and a free end axially spaced by a cage having a plurality of circumferentially spaced, axially extending ribs. The fixed end is secured to a rigid mounting support, such as the housing of a turbine engine, and the free end supports a bearing journalling the shaft of the engine. The ribs allow the bearing to radially move relative to the housing. Whereas the known cantilever mountings have been found to be generally satisfactory for many applications, applicant has determined that they: have relatively high stresses at the junction of the ribs with the ends; are, in some instances, too long to fit in the available space; and are expensive to manufacture.